Developments of new Lowicryl resins for embedding biological specimens at even lower temperatures.

Two new Lowicryl resins have been developed for embedding biological materials at temperatures down to 210 K (hydrophilic K11M) and to 190 K (hydrophobic HM23). They have similar properties to Lowicryl K4M and HM20. The new resins were first tested for low temperature applications by the 'progressive lowering of temperature' procedure and this shows that the low viscosity of K11M and HM23 is favourable for the infiltration of biological specimens. Hardening is achieved through photo-polymerization at these lower temperatures. These properties make K11M and HM23 suitable for cryosubstitution of rapidly frozen material and it is speculated that the preservation of antigenicity may be further improved.